Brake device for sewing machines



Aug. 16, 1938. w. L. BARRON BRAKE DEVICE FOR SEWING MACHINES Filed sept. 19, 1936 2 Sheets-Sheet l Ww... fm1 y v 1% ,E ggg M.

Aug. 16, 1938. w. L. BARRoN I BRAKE DEVICE FOR SEWING MACHINES Filed Sept. 19, 1936 y Sheets-Sheet 2 i Patented Aug. 16, 193s UNITED STATES PATENT OFI-lcs` BRAKE DEVICE FOR SEWING MACHINES William L. Barron, Laurence Harbor, N. J., as-

signor to The Singer Manufacturing Company,

7 Claims.

This invention relates to sewing machines, and it has, as its primary object, to prevent accidental reciprocation ofthe needle during the winding of bobbins.

As commonly constructed, each sewing machine includes a main shaft, a handor balance-wheel normally secured thereto at one end, means actuated by the main shaft to reciprocate the needle-bar, and means, either manual or power, for rotating the balance-wheel and thereby the main shaft. It is also common practice to fit each machine with a bobbin-winder adapted to be operated either by the rotation of the balance Wheel or by the drive therefor.

Inasmuch as the bobbin-winding operation is separate and distinct from the sewing operation, it is desirable that, during the bobbin-winding operation, the stitching mechanism be rendered ineffective. Therefore it is customary to 20 provide friction clutch means between the balance-wheel and the main shaft so that the balance-wheel may be uncoupled from the shaft and be rotated idly thereon during the bobbinwinding operation.

In recent years improvements in sewing machines have made them so light running that the slightest sticking of the balance-wheel clutch, when released, or even the friction of the balance-wheel on the main shaft is sometimes sufcient to cause the needle-bar to be reciprocated.

Another object of this invention therefore is to provide means for preventing accidental reciprocation of the needle-bar during the bobbin-winding operation and so to construct such means that it may readily be applied, as an attachment, to sewing machines now in use.`

Still another object of the invention is so to construct the device that it will be rendered effective to maintain theneedle-bar stationary by the normaly operations incident to a bobbinwinding operation, and therefore will not impose any additional duty on the operator.

With the above and other objects in View, as will hereinafter appear, the invention comprises the devices, combinations and arrangements of parts hereinafter described in connection with the accompanying drawings which illustrate a preferred embodiment of the invention, and in whichz- Fig. 1 is a side elevation, partly in section, of a sewing machine embodying the present invention.

Fig. 2 is a left end View of a .portion of Fig. 1

showing in full lines, the parts in sewing position and the needle-bar restraining means in its ineffective position.

Fig. 3 is a fragmentary left end view of the machine illustrated in Fig. 1, showing the needle-bar restraining means in its effective position.

Fig. 4 is a detail perspective view of the needlebar restraining device showing it secured to the presser-bar of a sewing machine.

Fig. v5 is a horizontal sectional view taken on the line 5-5 of Fig. 3.

Fig. 6 is a detail perspective View of one of the elements of the needle-bar restraining means.

Referring more specifically to the drawings, the invention is disclosed as embodied in a sewing machine comprising a bed plate I, standard 2, overhanging arm 3 and head 4. Within the arm 3 isv journaled, in bearings 5 and 6, a main or needle-bar driving shaft I to the rear end of which is adapted to be secured a handor balance-wheel 8. The balance-wheel ispreferably formed with a hub 8a rotatably iournaled on a sleeve 9 secured to the shaft 1, by a pin I0. The balance-wheel is adapted to be rotated by any suitable means, such for example as by an electric motor M, the shaft `II of which carries a gear I2 which meshes with and drives a complemental gear I3 secured to the hub of the balance wheel. The sleeve 9 is formed with a shoulder I4 against which a corresponding shoulder I5. within the hub 8, is clamped by a` manually operated clamp screw I 6 having a knurled head I1. The clamp screw is threaded into the outer end of the sleeve 9 and bears against a washer I8 which in turn bears against the balance wheel 8 to force the shoulders I4 and I5 into driving contact. The shoulders I4 and I5 and the washer I8 and hub 8a form a friction clutch which, when in driving contact, causes the main shaft 'I to be rotated with the balance-wheel. A bobbin-winder W, shown partially in Fig. 2 is secured to a portion of the motor casing and is adapted to be operated by contact with an annular flange I9 formed on the balance wheel. Preparatory to a bobbin-winding operation the balance wheel clutchl is released so that the bobbin may be wound without rotating the main shaft and without actuating the parts connected therewith.

The above described drive, clutch and bobbinwinding means are of conventional form and are disclosed in detail in U. S. patent to W. J. Peets, No. 1,934,373, Nov, "I, 1933, to .which reference may be had for a more complete understanding thereof.

At its forward end, the shaft 1 has secured thereto a take-up actuating cam 2U. This cam carries a crank-pin 2| which is connected by a link 22 to a needle-bar 23 mounted in bearings 24 and 25 provided by the head 4. Thus, rotation of the main shaft effects reciprocation of the needle-bar and a needle 26 carriedthereby. A presser-bar 21, carrying a presser-foot 28, also is mounted in the head 4 and is urged downwardly by a spring 29 in the usual manner. A presser-lifting lever 30 is pivotally mounted on a stud 3| secured in the head 4 and has a cam surface 32 which engages beneath a finger 33 carried by a collar 34 secured to the presserbar. The collar 34 also has an arm 35 which projects at right angles to the nger 33 and which is slidingly fitted between the walls of a groove.36 milled in the head 4, (Figs. 1 and 5) thereby to prevent rrotation of the presser-bar in the head.

As hereinbefore indicated, this invention provides means to place an abnormal drag on a moving part of the machine and thereby prevent. reciprocation ofthe needle-bar during the bobbinwinding operation if the balance-wheel clutch should stick or should any other minor force tend to turn the main shaft when the clutch is released. This has been accomplished by providing a normally ineffective brake mechanism adapted to be rendered effective by the lifting of the presser-foot, which latter is done preparatory to a bobbin-.winding operation.

This brake device may be inthe nature of an attachment adapted to be applied to sewing machines now in use and comprises a spring arm 31 secured, as by a rivet 38, to one portion of a split collar v39 'adapted to be clamped to the presser-bar 21, as by a clamp-screw 40. The collar 39 is preferably made of two parts 39a and 39b so that it vmay readily be applied to machines now in use, without disassembling the machine. The part 39.a carries the spring arm 31 and is formed with an upwardly extending portion 4| having. an offset nger 42 adapted to slidingly t within the above mentioned milled groove 36 formed in the .head 4, thereby to prevent the collar 39 andthe parts carried thereby, .from turning on the presser-bar.

The springarm 31 is formed with a curved free end ,31a which, as shown in full lines in Fig. 2, is normally maintained out of the path of travel of the link 22 during the operation of the sewing machine. However, when the presserfoot is liftedfor the purpose ofv Winding bobbins, the cam portion ,32 of the lifter 30 engages anintermediate portion 319y of the spring arm 31,

and forces the end 31a thereof into the path of the lower end of the link 22, as shown in dotted lines in Fig. 2 and in full lines, Figs. 3 and 5. With the arm in this position, should the link tend to descend accidentally due to sticking of the balance-wheel clutch or from other causes, it will engage the free end 31EL ofthe arm 33 which will restrain the downward movement of the link and the needle-bar connected thereto suiiiciently to overcome the impositive movement thereof. Should the presser-foot be raised and the needle-bar be driven positively no damage will result as the brake arm 31 will merely be deected out of the path of the link 22 at each reciprocation thereof. v

From the foregoing it will be perceived that I have provided a simple means in the nature of an attachment, Whichmay be applied to machines ltory needle-bar; a presser-foot; driving means for said needle-bar; lifting means for said presser-foot; disconnecting means between said needle-bar and its driving means; means actuated by said driving means when it is disconnect- `ed from said needle-bar to wind bobbins; and

means, rendered effective by the actuation of said .presser-foot lifting means, to prevent accidental movement of said needle-bar after said disconnecting means has been actuated to disconnect said needle-bar from its driving means.

2. A sewing machine combining a reciprocatory needle-bar; a presser-bar; driving means for said needle-bar; lifting means for said presserbar; disconnecting means between-.said needlebar and its driving means; means actuated by said driving means when it is disconnected from said needle-bar to wind bobbins; and means secured tosaid presser-bar and rendered eifective by said presser-bar lifting means to prevent accidental movement of said needle-bar after said disconnecting means has beenactuated to disconneet said needle-bar from its driving means.

3. A sewing machine combining a head; a reciprocatory needle-bar therein; driving means for said needle-bar, including a rotary shaft and a crank-and-link mechanism between said shaft and said needle-bar; means to disconnect said needle-bar from its driving means; means actuated by said driving means when it is disconnected from said needle-bar to Wind bobbins; and a normally ineiTective impositive brake device located within said head and adapted to act upon a portion of said needle-bar driving means when said bobbin-winding means is in operation to prevent accidental reciprocation of said needle-bar.

4. A sewing machine combining' a reciprocatory needle-bar; driving means therefor 'comprising a rotary crank and a link connecting the crank with said needle-bar; means to disconnect said needle-bar from its driving means; means actuated by said driving means when it is disconnected from said needle-bar to Wind bobbins; and aspring brake device acting' on said link when said bobbin-winding means is in. operation, to prevent accidental reciprocation of said needle-bar.

5. An attachment for sewing machines having a reciprocatory needle,l driving means theref'ona' presser-bar, means to disconnect said needle from its driving means, and means actuated by said driving means when it is disconnected from said needle to wind 'bobbins; comprising a spring brake device adapted to be secured to said presserbar and to engage said needle driving means to prevent accidental reciprocation of said needle when it is disconnectedfrom its driving means.

6. An attachment for sewing machines having a reciprocatory needle-bar, a presser-bar, driving means, including a power driver, for said needlebar, lifting means for said presser-bar, disconnecting means betweenl said needle-bar and-its driving means, and means actuated by said driving means when it is disconnected from -lsaid needle-bar to wind bobbins; comprising a collar adapted to be secured to said presser-bar; and a spring arm carried by said collar, said arm having a portion adapted to lie within the range of movement of said presser-bar lifting means whereby said arm will be shifted by said lifting means into the path of movement of a portion of said needle-bar driving means, thereby to prevent accidental reciprocation of said needle-bar after said disconnecting means has been actuated to disconnect the needle-bar from its power driver.

'7. An attachment for sewing machines having a head, a presser-bar, a reciprocatory needle,

means including a prime mover for driving said needle, and means to disconnect said needle from said prime mover; said attachment comprising a split collar adapted to be secured to said presserbar; a nger projecting laterally from said collar and engaging a xed portion of said head to prevent rotation of said collar on said presser-bar; and a spring arm secured to said collar and having a portion adapted to engage said needle driving means to prevent accidental reciprocation of said needle when it is disconnected from said prime mover.

WILLIAM L. BARRON. 

